Analysis of Dry-Wet Climate Change Characteristics and Main Influencing Factors in Main Grain Producing Area of Tibet from 1980 to 2021

Based on the daily meteorological observation data of seven meteorological stations in southern Tibet from 1980 to 2021 (April-October), the temporal and spatial variation characteristics and influencing factors of aridity index ( AI ) in the growing season of major grain producing areas in Tibet were studied by using climate tendency rate, Mann-Kendal test, Morlet wavelet analysis, GIS hybrid interpolation method, Pearson correlation coefficient, contribution rate analysis and other methods. The results showed that the average AI in the main grain producing areas of Tibet was 1.7, which belonged to the semi-arid area, and the overall trend was decreasing (humidifying) (-0.036/10 a). The linear decreasing trend was different in different regions, and the area around Lhatse County was the most significant (-0.26/10 a). AI had no obvious abrupt change, and had long- and medium-term fluctuation characteristics of 24 years, 6 years. The spatial distribution was uneven, and had the characteristics of ‘shrinking arid area and expanding humid area . The contribution rates of the main climate influencing factors of AI varied in different regions. In general, the contribution rates after quantification was as follows: precipitation (34.9%)>relative humidity (28.4%)>sunshine (19.9%)>maximum temperature (12.4%).

Petrogenesis and Tectonics of the Naruo Porphyry Cu(Au) Deposit Related Intrusion in the Duolong Area,Central Tibet

The Duolong area is the most important part of the Western Bangong-Nujiang Suture Zone porphyry Cu（Au） metallogenic belt, in Tibet, China. Here new detailed data are presented from LAICP-MS zircon U-Pb, whole-rock geochemical, and in-situ zircon Hf isotope analyses for igneous rocks in the large Naruo deposit（2.51 Mt of Cu and 82 t of Au） which is located ~2 km NE of the Duolong（Duobuza and Bolong） super-large gold-rich porphyry copper deposit. We integrated our results with previous research of other porphyry deposits in the Duolong area and have identified the timing, geodynamic setting, and petrogenesis of the mineralization-associated magmatic events. Based on the measurements, the Duolong area porphyry Cu（Au） deposit formations are associated with Early Cretaceous intermediate-felsic magmatism, which is consistent with U-Pb zircon ages of 120 Ma. All the main intrusive rocks in the ore-concentrated area have similar lithogeochemical characteristics; they show a relative enrichment in both light rare earth elements（LREEs） and large-ion lithophile elements（LILEs： Rb, Ba, K, etc.） and relative depletion in both heavy rare earth elements（HREEs） and high field strength elements（HFSEs： Nb, Ta, Zr, Hf, etc.）. Moreover, the granite porphyry shows positive εHf（t） values between 1.38–7.37 suggesting that magmas were potentially derived from the partial melting of a depleted mantle wedge that had been metasomatized by subducted slab-derived fluids or melts. This paper points out that the formation of the porphyry-epithermal Cu（Au） deposit in the Duolong area was dominated by northward subduction of the Bangongco Tethys Plate beneath the Qiangtang block in the Early Cretaceous（124–114 Ma）, when the subducted oceanic crust reached 50–70 km underground and generated different degrees of phase transformation, which lead to a melt produced by dehydration of amphibole minerals, a metasomatized mantle wedge, and induced mantle partial melting that produced the magma. Those deposits occurred in a continental arc tectonic setting, which is similar to the continental margin arc environment of the ocean-continent subduction setting of the Andes metallogenic belt in South America.

The Major Two-stage Shortening Deformation of the Northern Tibet and Tian Shan Area Since the Latest Oligocene

It seems to be progressively recognized that the stress of the India-Asia convergent front can be transferred rapidly through the southern and central Tibetan lithosphere to the northern Tibet, hence leading to the crustal thickening deformation there during or immediately after the onset of the India-Asia collision（ca.55 Ma）.This study focuses on the late Cenozoic deformation and tectonic uplift of the northern Tibet and Tian Shan area.Detailed compilations of a variety of proxy data from sediments and bedrocks suggest that the northern Tibet and Tian Shan area underwent one stage of approximately synchronous widespread contractile deformation since 25–20 Ma, which seemed to decrease at circa 18 Ma as revealed by low-temperature thermochronological data.The latest Oligocene-early Miocene was also significant basin-forming episodes when many intermontane subbasins began to receive syntectonic sedimentation in the northeastern Tibet.Subsequently, the other phase of compressional deformation began to encroach more widely into the northern Tibet and Tian Shan area in episodic steps or continuously from 16–12 Ma to present.

Characteristics of Metamorphic Rock Magnetic Fabrics in the Nyalam Area of the Southern Tibet and Its Geological Significance, China

This paper reports Precambrian rock magnetic fabrics in the Nyalam area of southern Tibet. The analytical results of magnetic fabrics show that the values of H are high （〉 10% in general）, so the ductile deformations of the Precambrian rock are strong. The orientation of the maximum principal stress inferred from the minimum magnetic susceptibility is nearly S-N, NE-SW and NW-SE. The Flinn diagram of the magnetic fabrics show that the strain pattern is oblate and constrictional type. Magnetic foliation of great majority of rock samples is well developed and the magnetic lineation is poor and the magnetic susceptibility ellipsoid is flattened. The magnetic lineation of the minority rock samples is well developed and the magnetic foliation is poor and the magnetic susceptibility ellipsoid is prolate. According to the geological field and the magnetic fabrics, there are 3 times tectonic stress field in SN directed extruding, NW-SE directed extruding, NW-SE directed extension. It shows that the Nyalam area has undergone process the orientation of SN, NW-SE nappe structure and NW-SE directed extension structure. The change of tectonic stress is reflected by the field characteristics of the Precambrian rock magnetic fabrics that is the direct responding result of the arc-continental, continent-continental collision between the India and Asian continents in the late part of the Late Cretaceous to Late Eocene and subsequently shifted to intra-continental convergent, the plateau uplifting and extension structure stage since the Late Eocene.

Land Use Change and Its Effect on Environment Based on Farmers’Behaviors: A Case Study in Agricultural Areas of Tibet, China

In the case study in Agricultural Area of Tibet, the process and characteristics of farmers' land use were surveyed by semi-structural interview questionnaire. By comparing the change of land covers and farmers' land decision in two periods, the spatial connection of them was obtained. And the relations among farmers' land decision, land use change and environment were examined by calculating emergy and value flow. The results show that: hunting the maximal profits is the primary aim of farmers' land decision; farmers' land decision is incompatible with sustainable land use presently; farmers' land decision and land cover can be embodied spatially by each other; the change of farmers' land decision can be monitored by observing the change of land cover, and the sustainability of farmers' land decision can be appraised by calculating emergy and value flow.

Confinement and Semi-confinement Raising Fattening Technology of Yaks in Agricultural Areas of Tibet

In the study, confinement and semi-confinement raising fattening technology of yaks in agricultural areas of tibet were analyzed. And several suggestions for improving the efficiency of yak raising were put forward. Aiming at providing the reference of healthy raising and sustainable development of yaks in the agricul- tural areas of tibet.

Analysis on Characteristics of Seismic Damage of the Nepal M_S8.1 Earthquake in the Tibet Area of China

On April 25,2015,a M_S8. 1 earthquake occurred in Nepal. In the Tibet area of China,this earthquake caused heavy casualties and damage to housing,roads,communications,other lifeline engineering, water conservancy and other infrastructure. This paper introduces the basic situation of the earthquake,and based on the investigation and assessment of seismic intensity,the damage of the disaster area is analyzed,and building types and damage to the lifeline systems and various industries are given. Through the analysis of the characteristics of the earthquake disaster,this paper points out the existing problems in seismic fortification,and finally puts forward proposals for the prevention and control of earthquake geological disasters, scientific planning for the restoration and reconstruction,strengthening earthquake prevention and disaster reduction propaganda,improving the awareness of earthquake preparedness in the agricultural and pastoral areas,strengthening the guidance and supervision of housing construction in rural areas to reduce the casualties and losses,and promoting the harmonious development of economy in Tibet.

Richly Endowed Qamdo Area In East Tibet

Ｒｉｃｈｌｙ Ｅｎｄｏｗｅｄ Ｑａｍｄｏ Ａｒｅａ Ｉｎ Ｅａｓｔ ＴｉｂｅｔＲｉｃｈｌｙＥｎｄｏｗｅｄＱａｍｄｏＡｒｅａＩｎＥａｓｔＴｉｂｅｔ￥ＬＩＭＩＮＧＳＥＮＥａｓｔＴｉｂｅｔｂｏａｓｔｓｔｈｒｅｅｒｉｖｅｒｓｆａｍｏｕｓｉｎＡｓｉａ：ｔｈｅＪ...

THE LAST TRADE CARAVAN IN TIBET WANGCHEN WAS BUSY IN AN AGRICULTURAL AREA

Setting off from Lhasa we followed Lhasa River,passing through Chushur County,then,driving along the banks of the Yarlung Tsangpo River,we finally arrived at Nyemo Bridge.Next we headed northward and into a long valley.Finally,we reached Nyemo County.Although it was not a big county,it looked much more prosperous than Palgon County.A large government office building greeted us in a main street offering shops,both big and small,as well as restaurants-which also caught our eye.Nevertheless,the wandering la...

Phanerozoic Paleomagnetism Characteristics of the Qomolangma Area in Tibet

This paper conducts systematic test research on the 2920 paleomagnetic directional samples taken from Ordovician-Paleogene sedimentary formation in the north slope of Qomolangma in south of Tibet and obtains the primary remanent magnetization component and counts the new data of paleomagnetism the times. Based on the characteristic remanent magnetization component, it calculates the geomagnetic pole position and latitude value of Himalaya block in Ordovician- Paleogene. According to the new data of paleomagnetism, it draws the palaeomagnetic polar wander curve and palaeolatitude change curve of the north slope of Qomolangma in Ordovician-Paleogene. It also makes a preliminary discussion to the structure evolution history and relative movement of Himalaya bloc. The research results show that many clockwise rotation movements had occurred to the Himalaya block in northern slope of Qomolangmain the process of northward drifting in the phanerozoic eon. In Ordovician-late Cretaceous, there the movement of about 20.0~ clockwise rotation occurred in the process of northward drifting. However, 0.4° counterclockwise rotation occurred from the end of late Devonian epoch to the beginning of early carboniferous epoch; 6.0° and 8.0° counterclockwise rotation occurred in carboniferous period and early Triassic epoch respectively, which might be related with the tension crack of continental rift valley from late Devonian period to the beginning of early carboniferous epoch, carboniferous period and early Triassic epoch. From the Eocene epoch to Pliocene epoch, the Himalaya block generated about 28.0° clockwise while drifting northward with a relatively rapid speed. This was the result that since the Eocene epoch, due to the continuous expansion of mid-ocean ridge of the India Ocean, the neo-Tethys with the Yarlung Zangbo River as the main ocean basin closed to form orogenic movement and the strong continent-continent collision orogenic movement of the east and west Himalayas generated clockwise movement in the mid- Himalaya area. According to the calculation of palaeolatitude data, the Himalaya continent- continent collusion orogenic movement since the Eocene epoch caused the crustal structure in Indian Plate- Himalaya folded structural belt- Lhasa block to shorten by at least 1000 km. The systematic research on the paleomagnetism of Qomolangma area in the phanerozoic eon provides a scientific basis to further research the evolution of Gondwanaland, formation and extinction history of paleo- Tethys Ocean and uplift mechanism of the Qinghai-Tibet Plateau.

THE GEOCHEMISTRY CHARACTERISTICS OF BLUESCHIST IN THE GANGMAR AREA, QIANGTANG BLOCK, TIBET

The Qinghai—Xizang (Tibet) Plateau was assembled by the successive accretion of continental and arc terranes to Asia during the Palaeozoic, Mesozoic and early Tertiary. From north to south, the Plateau was divided into four terranes (from north to south): Songpan\|Garze, Qingtang, Lhasa and India terranes. The Qiangtang terrane was divided into two parts by Chabu\|Shuanghu suture: Northern Qiangtang and Southern Qiangtang blocks. It was believed that there is a suture as Palaeotethyan suture between the two blocks from Lungmu lake to Chabu, to Shuanghu, to Langcangjiang, but some geologists opposited this opinion, such as Wang Chengshan et al.(1987) and Deng Wanming et al.(1996). The blueschists that bear the typical glaucophane were found in the Gangmar Area in summer of 1997. The blueschists consist of glaucophane, crossite, phengite, actinolite, epidote, sphene ,rutile, and so on. Blueschists show nappe structures in enclosing rocks, and thrust over Tertiary from north to south.The age of blueschist is 275～285Ma which stand for the metamorphic age of blueschist. The geochemical contents of blueschists are the following: SiO\-2 is 45 37%～53 82%, Na 2O>K 2O, K 2O+Na 2O are 3 72%～7 61%, Na 2O/K 2O is 1 70～19 67, MnO is 0 16%～0 22%, FeO+Fe 2O 3 are 11 12%～14 27%, TiO 2 is 2 34%～4 28%, P 2O 5 is 0 34%～1 03%. From the contents, SiO 2 is inverse relation with K 2O+Na 2O, K 2O and FeO+Fe 2O 3. In the SiO 2\|K 2O+Na 2O diagram, the blueschists fall in the field of Alkali basalt; in the TiO 2\|MnO(10\|P 2O 5×10 triangular diagram, these plot within the Ocean Island Basalts(OIB) field. The whole REE content is (117 03～390 97)×10 -6 , LREE/HREE is 5 05～9 80, the REE diagram shows the feature that LREE is rich and HREE is depleted, this is similar to the OIB. In the spidergram of trace elements show the same characterristics as the OIB. Meanwhile, the trace elements ratios, such as Ba/Nb, La/Nb, Nb/Th, Nb/Y, Zr/Y, Zr/Nb, Hf/Sm, Ta/Hf, Nb/Ta, Nb/U, suggest the tectonic setting is OIB. On the basis of these materials, the blueschists are akin to within\|plate ocean island basalts. This shows that there is a ocean or oceanic basin in the Chabu\|Shuanghu belts and the formation of blueschists is the quicky subduction of the Ocean Island Basalts in Early Permian between the Gondwana and Eurasia continents. It demonstrated, therefore, that the Chabu\|Suanghu suture exists and may extend to the east to Lnagchangjiang, and may extend into Thailand\|Malaysia Peninsula.

Carbon Isotope Excursions and Paleo-Oceanography of the Ordovician–Silurian Boundary Carbonate Rocks from the Xainza Area, Tibet

Objective The Ordovician–Silurian transitional period is a special time when the global paleo-environment changed greatly.It witnessed the first mass extinction as of Phanerozoic period and glaciations that occurred frequently at a large scale in a very short time,which has thus attracted much attention among geoscientists at home and abroad.

Magmatic Evolution and Mineralization of Porphyry Copper-Gold Deposits in the Duolong Ore Concentration Area, Tibet

The Bangong Lake-Nujiang River metallogenic belt is located between the Qiangtang Block and Lhasa Block, and the Duolong ore concentration area is located in the western section of the Bangong Lake-Nujiang River metallogenic belt. Till now, several large and super large copper-gold deposits, such as Duobuza, Bolong, Dibaonamugang, Naruo and Rongna deposits have been discovered in this area, mainly porphyry copper-gold ones.

Geochemical Characteristics of Cenozoic Basaltic High-K Volcanic Rocks from Maguan Area, Eastern Tibet

The major element, trace element and Nd-Sr isotopic composition of Cenozoic basaltic volcanic rocks from the Maguan area, eastern Tibet, indicates that the volcanic rocks are enriched in alkalis, especially K (K-2O up to {3.81%}) and depleted in Ti (TiO-2={1.27%}-{2.00%}). These rocks may be classified as two groups, based on their Mg+# numbers: one may represent primary magma (Mg+# numbers from 68 to 69), and the other, the evolved magma (Mg+# numbers from 49 to 57). Their REE contents are very high (∑REE={155.06}-{239.04}μg/g). Their REE distribution patterns are of the right-inclined type, characterized by LREE enrichment [(La/Yb)-N={12.0}-{19.2}], no Ce anomaly (Ce/Ce+*={1.0}), and weak negative Eu anomaly (Eu/Eu+*={0.9}). The rocks are highly enriched in Rb, Sr and Ba ({59.5}-{93.8} μg/g, 732-999 μg/g, and 450-632 μg/g, respectively), high in U and Th ({1.59}-{2.31} μg/g and {4.73}-{8.16} μg/g, respectively), and high in Nb, Ta, Zr and Hf (70-118 μg/g, {3.72}-{5.93} μg/g, 215-381 μg/g, and {5.47}-{9.03} μg/g, respectively). In the primitive mantle-normalized incompatible element spidergram, Nb, Ta, Zr, Hf and P show positive anomalies, whereas Ba, Ti and Y show negative anomalies. The {{}+{87}Sr/+{86}Sr} ratios range from {0.704029} to {0.704761}; {{}+{143}Nd/+{144}Nd} from {0.512769} to {0.512949}; and εNd from {+2.6} to {+6.1}. These geochemical features might suggest that the potential source of the basaltic high-K volcanic rocks in the Maguan area is similar to the OIB-source mantle of Hawaii and Kergeulen volcanic rocks.

Revision of the Genus Conophyllia d'Orbigny 1849(Anthozoa, Scleractinia, Triassic) and Conophyllia from the Renacuo area of Gêrzê, Tibet

There have been divergent opinions on whether Conophyllia develops synapticulae and dissepiments since its erection in 1849, with different views existing on the morphology of columella in Conophyllia.This paper presents a comprehensive review of Conophyllia, and revises the diagnosis according to new material from the Renacuo area of Gêrzê, Tibet.The revised diagnosis emphasises the following features： solitary coral; abundant radial elements subequal in thickness, lateral faces with granules and synapticulae; parietal, papillar or incompact columella, a few species lacking in columella; developed dissepiments.Individuals of Conophyllia have laminar septa of Triadophyllum type in earlier ontogenetic stages, while their septa in later ontogenetic stages are more fenestrate.The geological and geographical distribution of this genus is discussed, with five species of Conophylliafrom the Renacuo area of Gêrzê, Tibet being described and illustrated, including one new species and two in open nomenclatue.

Deep-derived enclaves (belonging to middle-lower crust metamorphic rocks) in the Liuhe-Xiangduo area, eastern Tibet: Evidence from petrogeochemistry

Petrological and geochemical studies of deep-derived enclaves from the Liuhe-Xiangduo area, eastern Tibet, showed that the enclaves involve five types of rocks, i.e., garnet diopsidite, garnet amphibolite, garnet hornblendite, amphibolite and hornblendite, whose main mineral assemblages are Grt+Di+Hbl, Grt+Pl+Hbl+Di, Grt+Hbl+Pl, Pl+Hbl, and Hbl+Bt, respectively. The enclaves exhibit typical crystalloblastic texture, and growth zones are well developed in garnet (Grt) in the enclaves. In view of major element geochemistry, the deep|derived enclaves are characterized by high MgO and FeO+*, ranging from {12.00%} to {12.30%} and {8.15%} to {10.94%}, respectively. The protolith restoration of metamorphic rocks revealed that the enclaves belong to ortho-metamorphic rocks. The REE abundances vary over a wide range, and ∑REE ranges from {53.39} to {129.04} μg/g. The REE patterns slightly incline toward the HREE side with weak LREE enrichment. The contents of Rb, Sr, and Ba range from {8.34} to 101μg/g, 165 to 1485 μg/g, and 105 to 721 μg/g, respectively. The primitive mantle-normalized spider diagrams of trace elements show obvious negative Nb, Ta, Zr and Hf anomalies. Sr-Nd isotopic compositions of the enclaves indicated that the potential source of deep-derived enclaves is similar to the depleted|mantle, and their {({}+{87}Sr/+{86}Sr)-i} ratios vary from {0.706314} to {0.707198}, {({}+{147}Nd/+{144}Nd)-i} ratios from {0.512947} to {0.513046}, and {ε-{Nd}(T)} values from {+7.0} to {+9.0}, respectively. The potential source of the enclaves is obviously different from the EM2-type mantle from which high-K igneous rocks stemmed (the host rocks), i.e., there is no direct genetic relationship between the enclaves and the host rocks. Deep-derived enclaves in the host rocks belong to mafic xenoliths, and those in the Liuhe-Xiangduo area, eastern Tibet, are some middle-lower crust ortho-metamorphic rocks which were accidentally captured at 20-50 km level by rapidly entrained high-temperature high-K magma, whose source is considered to be located at 50-km depth or so.

Ecological vulnerability analysis of Tibetan towns with tourism-based economy： a case study of the Bayi District

This paper provides a generalizable mode for the ecological vulnerability evaluation for tourism planning and development in high mountain areas.The Bayi District located in southeastern Tibet is taken as a typical town to study the conflict between the protection of natural ecological environment and the exploitation of tourism resources. Based on the Sensitivity-Recovery-Pressure(SRP) framework, a set of vulnerability evaluation systems for plateau tourism regions were developed. The spatial principal component analysis(SPCA), remote sensing and GIS technologies were integrated to apply for spatial quantification of evaluation index system. The ecological vulnerability of the Bayi District was divided into five levels: potential, mild, moderate,severe, and extreme, and our results showed that significantly severe and extreme vulnerability areas were mainly distributed throughout the southwestern and central northern alpine pasture and glacial zones.Potential and mild vulnerability areas were mainly distributed in the vicinity of the Yarlung Zangbo River tributary basin. Then three tourism development and environmental protection zones were classified and appropriate measures for the protection were proposed. It also provides a reference for the spatial distribution of a range of areas that require different protection measures according to ecological vulnerability classification.

Ecological Carrying Capacity of Tibet China ——Variety of Ecological Footprints from 1978 to 2002

Ecological footprint's theory and method are used to calculate and analysisthe ecological carrying capacity in Tibet. The results indicate: Tibet ecological footprint (2.1hm^2) keeps higher than countrywide average level (1.5 hm^2), and lower than global average level(2.4 hm^2); the result show that Tibet pasture ecological footprint is the most different with otherarea, and woodland is the second; Tibet ecological footprint grows from 1. 25 hm^2 in 1978 to 2.09hm^2 in 2002, which states that life level is improving continuously; GDP (per RMB 10~4 Yuan)ecological footprint reduces from 61. 9 hm^2 in 1978 to 4. 54 hm^2 in 2002, which states resourcesutilized ratio is increasing continuously.

A study of economic development in Tibet of China based on the ecological economic mode

The purpose of this paper is to study the issues on keeping the continuous development of Tibetan economy and the relative stability of its ecosystem. Hence, in order to achieve the object, the study analyzes the status quo of economic development in Tibet and the problems of resource exploitation. It especially discusses frailty of Tibetan eco-environment, and evaluates the contradictions between the traditional economic developing mode and the safety of plateau＇s ecosystem. It concludes that there is an inevitable clash between the development of Tibetan economy and the safety of plateau＇s eco-system; this problem cannot be avoided by any decision maker, Therefore, the character of Tibetan econvironment and the requirement of its economic development strategy determine that ecological economy developing mode is the only choice for Tibet. This paper suggests that it should be compensated by the national government to assure that Tibetan economy can keep a higher developing speed. In accordance with the feature of plateau eco-economy system and demand of Tibetan economic development, this paper also suggests several methods to apply the ecoeconomy developing strategy of Tibet.